Conclusions and Recommendations This thesis based research is concluded as

• A linear magnetic tape transport system which enables travelling tape regulation in closed loop control was developed.

• A rotary guider with dynamic tape path alternation was proposed and developed as a tension actuator. Strain gauge based tension sensor is developed and implemented to the system as the tension feedback.

• The transition of tension with the fixed angle of rotary guider (the fixed tape path) was investigated through experimental studies. The transition of tension was increasing as more length of tape was transported and it can be occurred due to the increase of torque of tape pack driving motor. It is concluded that the dynamics of tape pack driving motor is the primary factor to decide the state of change in tension. The angle of rotary guider shifts the level of tension. Higher travelling tape speed and angle of rotary guider generates generally greater tension. • Rotary guider with dynamic tape path alternation in closed loop control (a proportional gain

controller) enabled actuation of travelling tape tension and it is successfully regulated as prescribed. It is found that the dynamics of rotary guider is the major elements that influence to the state of change in tension, and they surpass the influence of tape pack driving motor dynamics to the tension.

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5.1.1 Development of Linear Magnetic Tape Transportation System

Both the hardware and the software of a linear magnetic tape transport system that enables the travelling tape tension actuation in closed loop control were developed. The travelling tape tension is actuated using the rotary guider using the surface friction guide between the tape and the rotary guider. The tension is measured using the strain gauge based tension sensor. The operations of the developed system including the tape transportation, rotary guider control, and monitoring and recording of measured tension from the tension sensor are commanded through GUIs on the control PC. However, the output signal of the tension sensor contains a significant amount of noise. Therefore, it is essential to implement a signal conditioner between the sensor and the MCU to eliminate the noise of the signal in order to measure the tension accurately.

5.1.2 Tension Transitions with Fixed Tape Path

The transitions of travelling tape tension during the handing process were investigated through experimental studies and measured using the combination of parameters in the travelling tape tension and the angle of the rotary guider. The angle of the rotary guider was fixed during the transportation process. The measured tensions were analysed using offline MATLAB. Through experimental studies, it was found that the transition of tape tension relies heavily on the dynamics of the rotary guider and the greater tension is applied to the travelling tape with a higher travelling speed. The level of tension can be shifted using the rotary guider. As a general trend, the higher rotation angle of the rotary guider generates greater tension. During the tape transportation from BOT to EOT, the wrap angle of tape around the rotary guider increased 7 degrees with any angle of rotary guider. However, the increase of wrap angle around rotary guider has a minor effect on the tension change;, this was figured out by comparing transitions of tension between the presence and absence of the rotary guider. In this system, the travelling speed was set as an averaged travelling speed and the actual speed increases as tape is transported during the transportation process. Therefore, it can be concluded that the regulation of the travelling speed of tape can reduce the gradient of tension and increase tension. Further, the driving source of tape packs are brushed DC motors and when the tape is transported, one of DC motors that correspond to the transporting direction is driven; the other motor is still connected to the tape pack, but disabled. Therefore, rotation of both DC motors can be affected by the tension change phenomena. For this reason, it is strongly recommended to replace the brushed DC motors with brushless DC motors to enable a smooth rotation of the tape pack driving motor and also to develop the travelling tape speed controller.

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5.1.3 Dynamic Tape Path Alternation with Rotary Guider

Based on the calibration of tension transitions with a fixed tape path, the tension controllable regions of the rotary guider with travelling speed were calculated. A closed loop control algorithm for the rotary guider controller that is a proportional gain controller was designed and developed based on the calibrated tension controllable regions. An open loop control algorithm that rotates the guider to a certain angle with particular intervals was also developed in order to investigate the effectiveness of wrap angle regulation of the rotary guider. Experimental studies were carried out to evaluate the developed controllers. Through experiments, it was found that an open loop control algorithm reduces the increase of tape tension due to an increase of tape pack driving motor torque as the tape is transported, especially at lower travelling speeds of the tape. The closed loop control algorithm has an ability to regulate the tension as targeted without relying on the dynamics of the tape pack driving motor. The performance of tension regulation with designed controllers is significant at lower tape travelling speeds. While at higher travelling speed, the performance of the designed controller is degraded significantly. The advanced rotary guider controllers such as the robust logic controller need to be developed in order to improve the accuracy of tension regulation. Further, increasing the number of rotary guiders can e drastically improve the tension controllability of the rotary guider. However, since this tension actuation mechanism uses the surface friction between the tape and the rotary guider, higher tension might damage the tape; therefore, there is a trade-off between tension controllability and durability of tape.